Relationship between oocyte morphology and fertilization rate after ICSI - Revista Brasileira de Ginecologia e Obstetrícia

PURPOSE: to verify the possibility of identifying oocytes that would result in a higher fertilization rate. METHODS: retrospective analysis of the fertilization rate after ICSI of 957 oocytes in metaphase II according to three morphology parameters: cytoplasm inclusions, thickness of the perivitelline space, and fragmentation of the first polar body. Oocytes were obtained from 115 cycles performed among 107 women attended at the “Centro de Reprodução Humana de Campinas”, from April to December of 2004. For the statistical analysis of differences in the fertilization rate between ‘normal’ oocytes and those presenting each alteration, the chi2 test was used with confidence levels of 5 and 10%. RESULTS: no significant difference in fertilization rate was observed regarding characteristics of the polar body or thickness of the perivitelline space. Fertilization rate among oocytes with perivitelline space with debris was 14 percentage points lower than among oocytes with absent space (p=0.055) and the rate among oocytes with granular cytoplasm was seven percentage points lower than among oocytes with normal cytoplasm (p<0.10>0.05). CONCLUSIONS: the morphological parameters of oocytes currently being evaluated do not allow us to clearly distinguish those that would lead to a higher fertilization rate and could be used in clinical practice.